Control of cell division is the most crucial aspect of cell biology which is relevant to the etiology of neoplasia in animals and human beings. A cancer cell differs from a normal cell in many aspects, two of which are the loss of density-dependent inhibition of cell division and abnormal cellular morphology. The proposed research concerns the study of control of cell division in bacteria as a model system. Bacterial mutants defective in the synthesis, assembly and degradation of the cell surface polymers will be isolated and studied both biochemically and genetically. Antibiotics which specifically inhibit the synthesis of bacterial cell envelope will be used for mutant selections. Studies on the mechanisms by which drug-resistant mutants may escape from the killing by these antibiotics may lead to a better control of infectious diseases.